The document US 2005/0052657 illustrates a method and an apparatus for executing the scanning of a tire for vehicle wheels mounted on a balancing machine. A light source emits a laser light beam on the surface of the tire. Such beam is reflected by the surface and captured by a CCD receiver. The receiver generates position signals based on the point of impact of the reflected beam and transmits them to a computer. The light source and the receiver are mounted on a support which can rotate around a respective pin and/or translate, moved by a suitable motor. The light source emits the light beam which defines a point of light on the tire. The light beam is reflected, passes through a focusing optical system up to a sensitive element of a CCD sensor, both part of the CCD receiver. The reflected light beam, directed by the optical system, impacts a specific zone of the CCD sensor, a function of the distance. The above-described apparatus allows scanning the entire surface of the tire due to the possibility for the support (with emitter and receiver) to be moved in rotation around the respective pin and/or in translation and allows acquiring an entire series of data of said tire (eccentricity, wear, conicity, etc.).
The Applicant has observed that such apparatus is mechanically complex and costly, in particular due to the presence of motors and structures such as to allow the movement of the light source and of the CCD receiver alongside the tire (by means of the rotation around the pin and/or the translation). In addition, the Applicant has observed that, in the absence of such movements of the support, the apparatus described in US 2005/0052657 could not perform its own function, i.e. executing the scanning of the entire surface, given that the light beam is point-like.
The document EP 2 020 594, on behalf of the same Applicant, illustrates a method and an apparatus for determining the geometric size of a tire for vehicle wheels mounted on a balancing machine or on a tire changer. The apparatus comprises a light source capable of generating a planar light beam which comes to impact a strip of the surface of the tire. At each point of said strip, defined by the intersection of the planar beam of light with the tire, the light beam is reflected and decomposed. The reflected beam is captured by a receiver provided with a sensitive two-dimensional surface, of CCD or CMOS type. Such sensitive surface generates signals proportional to the position of each point, of the strip, reflected on said sensitive surface.
The Applicant recognizes that the solution described in EP 2 020 594 allows the simultaneous acquisition of a plurality of points belonging to said strip, maintaining the light source and the receiver fixed with respect to a rotation axis of the tire; however, the cost of such instrumentation, in particular of the sensor with sensitive two-dimensional surface and relative electronics, is very high and has a significant effect on the cost of the entire machine (balancing machine or tire changer).